persamaan garis yang melalui titik A(-1 , 7 ) dan B(2, -3) adalah

(y2-y1) / (y-y1) = (x2-x1) / (x-x1)
(-3 - 7) / (y-7) = (2- -1) / (x - -1)
-10 / (y-7) = (2+1) / (x + 1)
-10 / (y-7) = 3 / (x+1)
-10 (x+1) = 3 (y-7)
-10x -10 = 3y -21
10x+3y-21+10 =0
10x - 3y -11 = 0
atau
10x - 3y = 11